for·mal·i·ty / fôrˈmalətē/ • n. (pl. -ties) the rigid observance of rules of convention or etiquette: he retained the formality of his social background. ∎ stiffness of behavior or style: with disconcerting formality, the brothers shook hands. ∎ (usu. formalities) a thing that is done simply to comply with requirements of etiquette, regulations, or custom: legal formalities. ∎ (a formality) something that is done as a matter of course and without question; an inevitability: her saying no was just a formality, and both of them knew it.